Preparation And Analytical Application Of Electrochemical Sensors Based On Tubular Nanomaterials

As an analytical tool with low cost,small size,easy operation and high sensitivity,electrochemical sensors have enhanced performance compared with other analytical instruments.The core of the electrochemical sensor is a chemically modified electrode.In recent years,various nanomater ials such as carbon nanomaterials,metal nanomaterials,DNA,and halloysite nanotubes have been used as electrode modification materials due to their good biocompatibility,excellent conductivity,large specific surface area,and good adsorption capacity.Covalent organic frameworks(COFs),as an emerging organic crystal material,have attracted extensive attention in the field of electrochemical sensors due to their two-dimensional ordered planar grid structure,large specific surface area and high stability.Based on the various advantages of these materials,this paper constructs a series of electrochemical sensors to achieve sensitive detection of environmental pollutants and small biological molecules.It mainly includes the following four aspects of work:1.Preparation of amine-functionalized carbon nanotubes(CNTs)and acid chloride-functionalized graphene oxides(GO)by covalent bonding to form carbon nanotubes-Graphene oxide nanocomposites(CNT/GO).The CNT/GO nanocomposites were modified on the surface of glassy carbon electrode by dropping method,and L-glutamic acid and herring sperm DN A were modified to the surface of the electrode by electrodeposition to investigate the electrochemical behaviors of AC and DA.The electrochemical response of AC and DA increased linearly in the range of 2 to 600?mol·L^-1.The detection limits of AC and DA were 0.16?mol·L^-1 and 0.81?mol·L^-1(S/N=3),respectively.The sensor has practical value for the determination of AC and DA in real samples.2.PI-COF 101 was prepared by using melamine(MA)and pyromellitic anhydride(PMDA),then CNT/GO nanocomposite was dropped on the surface of the electrode,and PI-COF 101 was modified on the electrode to construct a novel PI-COF101/CNT/GO/GCE electrochemical sensor.Under the best term,the concentration of AC was linear with the peak current in the range of 0.9?800?mol·L^-1,and the detection limit is 0.28?mol·L^-1(S/N=3).The concentration of AP was linear with peak current in the range of 1?800?mol·L^-1,and the detection limit was 0.51?mol·L^-1(S/N=3).Because of its good selectivity and high sensitivity,the sensor has practical value for the determination of AC and AP in real samples.3.The amine-functionalized carbon nanotubes were modified on the surface of the bare electrode by simple drop-casting method.And PI-COF 102 was electrodeposited on the electrode surface,and then successfully dropped a layer of silver-polyaniline nanocomposite.A novel PI-COF 102/CNT/Ag NPs-PANI/GCE sensor was successfully fabricated.The electrochemical behavior of UA and A was investigated by differential pulse voltamme try(DPV).The concentration of UA in the range of 0.1 to 800?mol·L^-1 was linear with the peak current,and the detection limit was 0.083?mol·L^-1(S/N=3).The concentration of A is linear with the peak current in the range of 2 to 800?mol·L^-1,and the detection limit was 0.59?mol·L^-1(S/N=3).The sensor was applied to the detection of UA and A in human urine,and satisfactory results have been obtained.4.The halloysite nanotubes(HN T)were functionalized the amine group by using silane.The silver nanoparticles were electrostatically adsorbed on the amine functionalized HNT,and then the amine groups are functionalized to form HNT@Ag NPs nanocomposites.It was combined with the acid chlorided GO to form HNT@Ag NPs/GO nanocomposites.The HNT@Ag NPs/GO nanocomposites were dropped on the surface of the glassy carbon electrode,and the pyrrole was electropolymerized on the surface of the electrode to construct a Ppy/HNT@Ag NPs/GO/GCE modified electrode.Under the optimal experimental conditions,as the AC concentration increased from 4 to 37?mol·L^-1,the electrochemical response of AC increased linearly.The linear range of DA was 8 to 37?mol·L^-1,and the peak current of DA was increased by the increase in DA concentration.The detection limits of AC and DA were 0.94?mol·L^-1 and 1.06?mol·L^-1,respectively(S/N=3).The sensor was applied to the detection of AC and DA in human urine and acetaminophen tablets,and satisfactory results were obtained.